Abstract
The morphology of a submarine dune field developed in a tidal inlet that connects the Argen- tinean continental shelf with Anegada Bay (southern Buenos Aires province) was studied. The sediment circu- lation was inferred from the differential displacements of the bedforms evaluated by comparing consecutive surveys. An echosounder and a Phase Measuring Bathymetric System (PMBS) called GeoSwath were used to obtain a detailed submarine morphology. Large dunes, with heights between 4.5 and 5.0 m and from 100 to 120 m separating them, were present near the southern limit of the dune field at 24 m depth. These dunes move towards the outer part of the channel at a speed of 18 to 75 m year -1 . At the northern end of the dune field, at 21 m depth, the dunes are smaller, being 2.0 to 2.5 m in height and separated by 40 to 80 m. The smaller dunes move towards the interior of Anegada Bay at 18 to 36 m year -1 . The distribution of the water flow in the entire water column was obtained through a perpendicular profile of the channel by means of an ADCP. Maximum current speeds were 2 m s -1 , and were found during flood tide. The results obtained indicate a circulatory transport model of sedimentary sands, with the formation of ebb and flood deltas at both ends of the deep inlet throat, which lacks of unconsolidated sediments.
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